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      <title>Kafka的消费延迟 - 交互式测验</title>
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          <div class="quiz-container">
            <div class="quiz-header">
              <h1>Kafka的消费延迟 - 交互式测验</h1>
              <p>检验你对文档内容的理解程度</p>
            </div>
            <div id="quiz-content">
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      <script>
        const quizData = [
  {
    "question": "根据文档，以下哪项不是导致 Kafka 消费延迟的直接原因之一？",
    "options": [
      "消息在分区中的内部存储格式",
      "消费者处理消息的业务逻辑复杂",
      "Kafka Broker 负载过高",
      "消费者从 Broker 拉取消息时存在网络延迟"
    ],
    "correctAnswerIndex": 0,
    "explanation": "文档中明确列举了消费延迟的四个根本原因：消费者拉取消息的延迟、消息处理的延迟、Kafka Broker的负载以及消息积压。而消息在分区中的内部存储格式是 Kafka 的底层实现细节，并未在文档中被列为导致消费延迟的直接原因。",
    "source": "文档中「1. 消费延迟的产生原因」部分",
    "hint": "文档开头部分总结了导致消费延迟的几个关键因素，请回顾一下，哪一个选项不在此列？"
  },
  {
    "question": "在 Kafka 消费者配置中，`max.poll.interval.ms` 参数的核心作用是什么？",
    "options": [
      "设置消费者单次 `poll` 操作可以拉取的最大消息字节数。",
      "定义消费者自动提交位移的频率。",
      "控制两次 `poll` 调用之间的最大时间间隔，若超出该值，消费者可能被认为失效并触发重平衡。",
      "规定 `poll` 方法在没有新消息时等待的最长时间。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "`max.poll.interval.ms` 参数用于监控消费者的活跃状态。它定义了消费者在处理完一批消息后，再次调用 `poll()` 方法的最大允许间隔。如果处理消息的时间过长，超过了这个阈值，Kafka 的消费者协调器会认为该消费者实例已经“死亡”或无响应，从而将其踢出消费组，并触发重平衡（Rebalance）机制。",
    "source": "文档中「4. 消费者拉取消息的频率」部分",
    "hint": "思考一下，如果一个消费者因为业务逻辑复杂而长时间没有响应，Kafka 消费组会如何保证消息能够被其他成员继续处理？"
  },
  {
    "question": "当 Kafka 消费延迟主要是由消费者自身的应用程序逻辑引起时，以下哪个是文档中提到的最可能的原因？",
    "options": [
      "消费者的业务逻辑需要进行大量的计算或调用外部服务。",
      "Kafka Broker 的磁盘 I/O 性能不足。",
      "生产者发送消息的频率过低。",
      "Kafka 集群发生了网络分区。"
    ],
    "correctAnswerIndex": 0,
    "explanation": "文档在“Kafka 消费者的消息处理”一节中明确指出，“如果消费者的业务逻辑复杂，比如需要进行大量的数据计算或依赖其他系统（如数据库、外部服务等），可能导致延迟”。这是典型的发生在消费者端应用层面的延迟原因。其他选项则分别归因于 Broker 硬件、生产者行为或网络基础设施问题。",
    "source": "文档中「3. Kafka 消费者的消息处理」部分",
    "hint": "这个问题聚焦于消费者收到消息 *之后* 的处理阶段。在这个阶段，什么活动最有可能消耗大量时间？"
  },
  {
    "question": "在监控 Kafka 消费状态时，哪个指标最直接地反映了消费者落后于生产者的消息数量？",
    "options": [
      "`fetch.max.wait.ms`",
      "`Consumer Records Count`",
      "`offsetLag` (消费滞后)",
      "`auto.commit.interval.ms`"
    ],
    "correctAnswerIndex": 2,
    "explanation": "`offsetLag`（消费滞后）是衡量消费延迟的核心指标。它表示特定分区中，生产者最新写入消息的位移与该消费者组已提交的最新位移之间的差值。这个差值精确地代表了消费者尚未处理的消息数量。",
    "source": "文档中「7. Kafka 的消费延迟监控」部分",
    "hint": "文档最后一部分介绍了一个关键的监控术语，它的名字直接与“滞后”或“落后”相关。"
  },
  {
    "question": "根据文档对消费者拉取机制的描述，Kafka 消费者是通过哪个核心方法来主动从 Broker 获取消息的？",
    "options": [
      "`commitSync()`",
      "`poll()`",
      "`sendFetchRequest()`",
      "`processRecord()`"
    ],
    "correctAnswerIndex": 1,
    "explanation": "文档中明确指出，“在 Kafka 中，消费者通过调用 `poll` 方法拉取消息”。`poll()` 方法是消费者消费循环的入口和核心，它封装了向 Broker 发送拉取请求、获取消息并返回给调用者的整个过程。而 `sendFetchRequest()` 是 `poll()` 内部调用的一个步骤，`commitSync()` 用于提交位移，`processRecord()` 是处理单条消息的逻辑，并非拉取入口。",
    "source": "文档中「2. Kafka 消费者端的拉取机制」部分",
    "hint": "消费者需要定期地去“轮询”Broker 是否有新消息，这个“轮询”动作对应的方法名是什么？"
  },
  {
    "question": "除了网络延迟和处理请求过多，文档中提到的哪个与 Kafka Broker 自身硬件相关的因素可能导致消费者拉取消息变慢？",
    "options": [
      "消费者端未开启自动提交位移。",
      "Broker 所在服务器的磁盘 I/O 性能不足。",
      "消费者的 `max.poll.interval.ms` 设置过小。",
      "消费者的业务逻辑过于简单，处理速度过快。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "文档在「Kafka Broker 负载与磁盘 I/O」部分指出，Kafka Broker 在响应消费者拉取请求时，需要从磁盘上的日志文件中读取数据。如果 Broker 所在服务器的磁盘 I/O 性能成为瓶颈，将直接影响其读取数据和响应请求的速度，从而导致消费延迟。",
    "source": "文档中「6. Kafka Broker 负载与磁盘 I/O」部分",
    "hint": "Kafka 的消息是持久化存储的。当消费者请求消息时，Broker 需要从哪个物理介质上读取数据？这个介质的性能会是关键。"
  },
  {
    "question": "关于 Kafka 消费者的位移（offset）提交机制，以下哪项描述是正确的？",
    "options": [
      "`commitSync` 是一个异步提交方法，不会阻塞消费者线程。",
      "无论是否开启自动提交，位移提交的延迟都不会影响消费进度。",
      "开启自动提交后，位移提交的频率由 `auto.commit.interval.ms` 参数控制。",
      "`enable.auto.commit` 设置为 `true` 后，消费者仍然必须手动调用 `commitSync` 方法来提交位移。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "文档中明确说明，当 `enable.auto.commit` 设置为 `true` 时，Kafka 会在后台根据 `auto.commit.interval.ms` 参数设定的时间间隔自动提交位移。选项A描述与事实相反；选项B错误，位移提交延迟会影响消费进度；选项D错误，`commitSync` 是同步阻塞方法，`commitAsync` 才是异步非阻塞的。",
    "source": "文档中「5. 消费者的自动提交机制」部分",
    "hint": "当你选择“自动”完成一项任务时，通常会有一个配置项来控制“多久自动执行一次”。"
  }
];
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            const totalQuestions = quizData.length;
            const answeredCount = userAnswers.filter(a => a !== null).length;
            const wrongCount = answeredCount - correctCount;
            const skippedCount = totalQuestions - answeredCount;
            const accuracy = totalQuestions > 0 ? Math.round((correctCount / totalQuestions) * 100) : 0;
            const errorRate = totalQuestions > 0 ? Math.round((wrongCount / totalQuestions) * 100) : 0;

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                '<h2>答题报告</h2>' +
                '<div class="score-summary">' +
                '<div class="score-card">' +
                '<h3>得分</h3>' +
                '<p>' + correctCount + ' / ' + totalQuestions + '</p>' +
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                '<div class="score-card">' +
                '<h3>正确率</h3>' +
                '<p>' + accuracy + '%</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>错误率</h3>' +
                '<p>' + errorRate + '%</p>' +
                '</div>' +
                '<div class="score-card score-details">' +
                '<table>' +
                '<tr><td>正确</td><td>' + correctCount + '</td></tr>' +
                '<tr><td>错误</td><td>' + wrongCount + '</td></tr>' +
                '<tr><td>未答</td><td>' + skippedCount + '</td></tr>' +
                '</table>' +
                '</div>' +
                '</div>' +
                '<div class="report-actions">' +
                '<button id="review-btn">回顾测验</button>' +
                '<button class="primary" onclick="location.reload()">再试一次</button>' +
                '</div>' +
                '</div>';

            let reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }
            quizContentEl.insertAdjacentHTML('beforeend', finalScoreHtml);
            document.getElementById('review-btn').addEventListener('click', reviewQuiz);
        }

        function reviewQuiz() {
            const reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }

            document.querySelector('.quiz-body').style.display = 'block';
            document.getElementById('quiz-footer').style.display = 'flex';
            
            currentQuestionIndex = 0;
            loadQuestion();
            updateNavigationButtons(); // Ensure nav buttons are correctly displayed
        }

        // Event Delegation for options
        optionsListEl.addEventListener('click', (event) => {
            if (event.target && event.target.matches('li.option-item')) {
                // Check if the question has already been answered
                if (userAnswers[currentQuestionIndex] === null) {
                    const selectedIndex = parseInt(event.target.dataset.index, 10);
                    selectOption(selectedIndex);
                }
            }
        });

        prevBtn.addEventListener('click', goToPreviousQuestion);
        nextBtn.addEventListener('click', goToNextQuestion);
        hintBtn.addEventListener('click', showHint);
        
        // 初始加载
        loadQuestion();
      </script>
    </body>
    </html>
  